More than twenty five years after the discovery of human immunodeficiency virus (HIV), recent projections from the World Health Organization and the Joint United Nations Program on HIV/AIDS indicate that if the pandemic progresses at its current rate, there will be more than 30 million infections by 2011.
However, despite considerable research efforts for finding effective treatments for preventing HIV infections, the two recently tested preventive vaccines either have failed (Mc Elrath et al., 2008) or produced modest results (Rerks-Ngarm et al., 2009).
Jae-Sung Yu et al. (Clinical and Vaccine Immunology, November 2006, vol 13, No. 11, 1204-1211) described recombinant Mycobacterium smegmatis vectors constructed to express the HIV-1 group M consensus env gene CON6 either as a surface, intracellular, or secreted protein. The authors could demonstrate that, in mice, recombinant M. smegmatis was immunogenic for the induction of HIV-1 T-cell responses at mucosal surfaces.
Ke-Qin Xin et al. (Blood, 1 Jul. 2003, vol 102, No. 1, 223-228) described a recombinant Lactococcus lactis vector expressing the V2-V4 loop of HIV-1 Env on its cell surface. Oral immunization of mice with this vector induced:                both mucosal and humoral immune responses as shown by detecting high levels of HIV-specific serum IgG and fecal IgA antibodies; and        a cellular immune response as shown by an increased number of HIV-specific IFN-gamma-secreting cells.        
To be properly expressed on the L. lactis cell surface, gene segments of 1 kb or less could be used.
Most scientists involved in HIV pathogenesis and prevention feel that before testing HIV preventive vaccines or other biological compositions for preventing or treating HIV infection in human beings, it would be more constructive to test their counterparts in non human primates (Morgan C, et al., 2008). The non human primate of choice is the macaque rhesus and among macaques, it has now been conclusively shown that macaques of Chinese origin infected by the Simian Immunodeficiency Virus (SIV) 239 are the best model mimicking most of the clinical, virologic and immunologic aspects of the evolution of HIV infection in humans (Marcondes M C, et al. 2006; Stahl-Hennig C, et al. 2007; Chen S, et al. 2008).
Finally, the scientific community now agrees that, once an effective preventive biological composition or vaccine against SIV 239, is discovered in the macaque, it should in all probability be successfully adaptable to humans to protect them from AIDS.
Despite constant research efforts of the scientific community, preventive and therapeutic efficient strategies remain awaited to combat the worldwide AIDS pandemic.
Various bacteria have been described to have interesting adjuvanticity and immunomodulating properties upon administration to subjects. In particular, lactic acid bacteria have been reported to promote a tolerance effect on the immune system.
For example, WO 2006/123230 published on 23 Nov. 2006 in the name of Stallergenes S.A., describes the use of a bacterium selected from Bifidobacteria and lactic acid bacteria as an adjuvant in an immunogenic composition capable of inducing antigen-specific tolerance upon sublingual, perlingual or oral administration to a subject. The immunogenic composition is proposed to be used for treating allergies, auto-immune diseases or for preventing graft rejections.
Yet for example, WO 2009/093900 published on 30 Jul. 2009 in the name of Stichting Top Institute Food and Nutrition, describes a tolerogenic composition containing a substantial amount of lactic acid bacteria in the mid-log phase. This composition induces a non antigen-specific immune tolerance when administered to a subject. The composition is proposed to be used for preventing, delaying and/or treating conditions or diseases associated with inflammatory responses that can lead to tissue damage such as allergies, autoimmune diseases, and inflammatory diseases of the intestine.